What exactly do you mean by uniformity?
I mean than solid white and lighter gray image had magenta tint on the left side and greenish tint on the right.
Simply like this forum where there are white bars on the both sides, you could clearly see they were different tint.
Well, P3 is color space Apple Macs and better iPads as well as most iPhones use, so if you want your monitor picture to look anything like what you see in Apple build in displays, that is what you want from your monitor. And it should be calibrated as well unless you want to get colorimeter and calibrate it yourself, but still you need a monitor that has P3 gamut as close to 100% as possible. Very few monitors actually have that unless you want to pay astronomical price.
Dell U2720Q's I tried seemed to have not so good support for P3 out of the box and even this mode was well hidden and did not look very good at all. With my new LG 32UN880-B default DCI-P3 color mode is pretty good, and looks very close to the same as my MBA M1 side by side checking the same images. This is not either the most uniform display (very few are on my standards anyway
) but not even nearly as bad as those Dell's were and there is not obvious uniformity issues.
